Various conventional air cleaners utilizing fans and filters are known. The principle of these air cleaners is to make air pass through a filter compulsively using a fan so as to make the dusts in the air be captured by the filter, thereby cleaning the air. In most of the usual air cleaners, the fan and the filter are completely separated and wind made by the fan is blown to the filter. Japanese Laid-open Patent Application (Kokai) No. 8-206436 discloses an air cleaner based on a sirocco fan of which side wall is made of a filter so that air flow is made to pass through the filter from the inside to the outside thereof by rotating the impeller, thereby cleaning the air.